For forty-eight hours last week, a highly coordinated virtual “iMarch” on Washington promoting immigration reform swamped Twitter, generating thousands of tweets that landed more than a half billion times, according to organizers, makingit among the largest social media advocacy efforts.

Beyond showing the muscle behind pro-immigration forces, the event represented the culmination of years of savvy and relentless efforts by Latino activists to mobilize supporters through social media, and draw undocumented immigrants out of the shadows to maximize political leverage. Members of Congress critical of the immigration overhaul legislation being debated found their Twitter accounts inundated with hundreds of messages like this one directed at Republican Sen. Ted Cruz of Texas: “@TedCruz /I’m from TX & #iMarch b/c #immigration reform secures our borders and creates jobs Texas.” Cruz was bombarded with 300 tweets from pro-reform constituents.

In the past year alone, activists say social media platforms have been instrumental in bolstering voter registration among Hispanics who supported for Barack Obama, were key in efforts to mobilize the community at various junctures to step up pressure for immigration reform, and served as a vital resource to advise students on how to get temporary legal status through President Obama’s deferred action program, which offers a two-year reprieve from deportation. Applicants to the program have even used GPS evidence from Facebook check-ins on their mobile devices to document for the federal government that they meet the residency requirement and were in the country since June 15 of last year.

“We have been able to move the needle through social media and that is the measure of success,” says activist Elianne Ramos, a founder of LATISM.org, which was launched in 2009 as “Latins in Social Media” to develop cultural and political connections and communication within the community. The hashtag #LATISM, Ramos says, in now used more than 1 million times a week, reaching more that 10 million people.

Experts say that Hispanics - the fastest growing population in the United States - were among the earliest users of smart phones because of the demographic’s growing young population, and because many simply could not afford a computer. Today, 72 percent of Latino Internet users say they are on social media sites compared to 58 percent of all U.S. internet users, according to the Pew Research Hispanic Center. Breaking it down further, 54 percent of Hispanics regularly use Facebook compared with only 43 percent of white Americans. Nielsen found last year in its “The Hispanic Market Imperative” report that Hispanic consumers’ use of smartphones, television, online video, and social networking “make this group one of today’s most engaged and dynamic populations in the digital space.”

The most recent census put the self-identified Hispanic population in the United States at 52 million, and there are an estimated 11 million undocumented immigrants.

”Our numbers alone won’t guarantee the Latino community’s full potential without an active community, fully engaged across American economic and political life - that’s what social media has given us,” said Jason Llorenz, director of Innovation Policy, the Latino Information Network at Rutgers University.

Llorenz, who trains organizations on effective use of social media, added that Facebook, Twitter and Instagram all “offer followers real-time intelligence on what’s going on. Social media has become vital to the success of the movement.”

One of the biggest success stories of Latino social media use has been attributed to the so-called Dreamers, loosely defined as young adults brought to the U.S. as children, but who are now struggling for identity. They are strong proponents of the Dream Act, which is now part of the comprehensive immigration reform, and would expand access to higher education for undocumented high school graduates. They are young, tech savvy and highly organized.

A handful of undocumented high school and college students a few years back began seeking each other each other out through the online discussion forums, popular at the time. They eventually created www.dreamactivist.org, which is today a sophisticated public relations campaign and website aimed at humanizing these young adults and publicizing success stories. They encourage other students to make their undocumented status known - which could provide them a public embrace and protect them from deportation.

“Any impact we have achieved has been through social media,” said Juan Escalante, 24, a recent graduate of Florida State University, who was an early dream activist. An undocumented Venezuelan national whose parents brought him here on a short-term visa when he was 11 years old, Escalante was concerned about his future when he went looking for like-minded people online.

“Facebook and Twitter gave us a platform. We can show our followers what we are doing and we can mobilize online in minutes. We wouldn’t be anywhere without social media,” he says.

Their story caught to the attention Oscar-winning film-maker Davis Guggenheim who this spring released “The Dream Is Now,” a sympathetic portrait of the dreamers that he collaborated on with Laurene Powell Jobs, the widow of Steve Jobs. The film is free and has pinged around social media for weeks.

“Social media specifically and the Internet in general has allowed us to tell our personal stories - stories that are not being told in the news. It’s up to us,” says Jose Antonio Vargas, a journalist and activist, who catapulted to fame when he revealed his compelling story of rising in mainstream journalism as an undocumented Filipino immigrant.

Vargas, who founded defineamerican.com, says, “You travel around the country and you find that so many people simplify the immigrant population into ‘illegal Mexicans.’ Well, the story is much more complex. We are you. We are your neighbors. We are brothers and sisters and fathers and mothers. Social media has allowed us to put a face on an issue.”

Nine years ago, Maria Terese Kumar saw the potential of reaching Latinos online when she started www.VotoLatino.com from a Starbucks. Voto Latino is today is a powerhouse in the organizing and registering of Latinos, and works to engage young Latinos in the civic process through social media. At the time Kumar and co-founder Rosario Dawson were launching Voto Latino, “My Space” was the hottest online platform for young Latinos- and so they started there.

“We recognized immediately that Latino youth were the among the pioneers in smart phone use, and we took advantage of that,” she said. “They may not have had access to a computer but they all had smart phones. We saw that people wanted to see people, they wanted to be connected to their community culturally.”

Today, Kumar said she is most effective when her organization “creates moments” that the virtual community can rally around, such as this week’s imarch. “This is like having our own private television station to convey important messages - only more effective,” says Kumar, who estimates her group helped register hundreds of thousands of voters last year. “People are not sitting around watching TV all the time. But they are on smart phones.”

Going forward, organizers for the “imarch,” also known as the March for Innovation- a bi-partisan coalition of high profile tech entrepreneurs, Latino advocacy groups and politicians - say they will use the successful social template to ratchet up pressure on Congress and keep opponents on the defensive as the controversial reform bill wends its way through the House and Senate.

“This is a tool that we can use with increasing effectiveness down the road,” says Jeremy Robbins , director of the Partnership for a New American Economy, a pro-reform group started by New York City Mayor Michael Bloomberg, and which spear-headed the “imarch.” “We will be able micro-target, focusing on individual members of Congress whose vote we want…This is just the beginning.”

The social media push that took place last Wednesday and Thursday had the support of an array of celebrities, stars from the tech industry and prominent political figures such as Obama, Condoleezza Rice, Bill Clinton, Newark Mayor Cory Booker and Arnold Schwarzenegger, all of whom tweeted support for reform to millions of followers. The march also partnered with Obama’s OFA (Organizing for Action), which helped promote it and push traffic. The president tweeted a number of times to his 31 million followers - and at one point retweeted Jeb Bush.

Skeptics question the effectiveness of a social media invasion, as opposed to face-to-face lobbying or an old-style march on Washington with real boots on the ground.

But organizers and advocates are careful to note that this in no way replaces traditional form of activism. “This absolutely does exclude traditional methods - it enhances them,” Robbins said. “We had to face this was 2103, and there are ways to communicate that are different that they were 20 years ago - we want to be able to maximize all the ways we can to reach Congress and our supporters.”